Aqueous ink compositions

ABSTRACT

An ink composition comprising water, a water-dissipatable polyester, a disperse dye or a solvent soluble dye or a mixture of such dyes, a water-immiscible organic solvent and a water miscible organic solvent. The inks are useful in ink jet printers.

This invention relates to an ink jet printing process and to inks.

Inks containing water-soluble dyes, water and organic solvents are wellknown. For example Zeneca's British Patent application No. 2,275,479describes such inks and their utility in ink jet printing (“IJP”).

Inks containing a water-insoluble acrylic polymer and an oil soluble dyeare described in U.S. Pat. No. 4,680,332. These inks are suitable forpiezoelectric IJP but when they are used in thermal IJP they tend toblock printer nozzles giving poor quality images which have a “quilted”appearance.

WO91/06608 describes aqueous inks containing a polyester, water, apigment and a wax. Whilst these inks are useful in printing presses, thepigments they contain require intensive and expensive milling to makethem fine enough to pass through ink jet printer heads and the pigmentshave a tendency to settle out from the ink on standing for long periods.Furthermore, images formed from inks containing insoluble pigments aregenerally opaque and this limits their usefulness on overhead projectorslides.

WO95/34024 describes a process for preparing an optical filtercomprising a coloured cross-linked polymeric coating on a transparentsubstrate.

There is a need for inks which are suitable for thermal IJP, have highcolour strength and give clear, high water-fast images with high lightfastness when printed on a substrate.

According to the present invention there is provided an ink compositioncomprising water, a water-dissipatable polyester, a disperse dye or asolvent soluble dye or a mixture of such dyes, a water-immiscibleorganic solvent and a water miscible organic solvent.

The Water-Dissipatable Polyester

The water-dissipatable polyester may be prepared using conventionalpolymerisation procedures known to be effective for polyester synthesis.Thus, it is well known that polyesters contain carbonyloxy (i.e.—C(═O)—O—) linking groups and may be prepared by a condensationpolymerisation process in which an acid component (includingester-forming derivatives thereof) is reacted with a hydroxyl component.The acid component may be selected from one or more polybasic carboxylicacids, e.g. di- and tri-carboxylic acids or ester-forming derivativesthereof, for example acid halides, anhydrides or esters. The hydroxylcomponent may be one or more polyhydric alcohols or phenols (polyols),for example, diols, triols, etc. (It is to be understood, however, thatthe polyester may contain, if desired, a proportion of carbonylaminolinking groups —C(═O)—NH— (i.e. amide linking groups) by including anappropriate amino functional reactant as part of the “hydroxylcomponent”; such as amide linkages). The reaction to form a polyestermay be conducted in one or more stages. It is also possible to introducein-chain unsaturation into the polyester by, for example, employing aspart of the acid component an olefinically unsaturated dicarboxylic acidor anhydride.

Polyesters bearing ionised sulphonate groups may be prepared by using atleast one monomer having two or more functional groups which willreadily undergo an ester condensation reaction (e.g. carboxyl groups,hydroxyl groups or esterifiable derivatives thereof) and one or moresulphonic acid groups (for subsequent neutralisation after polyesterformation) or ionised sulphonate groups (i.e. neutralisation of thesulphonic acid groups already having been effected in the monomer) inthe synthesis of the polyester. In some cases it is not necessary toneutralise sulphonic acid groups since they may be sufficiently strongacid groups as to be considerably ionised in water even without theaddition of base. Often, the sulphonic acid or ionised sulphonatecontaining monomer is a dicarboxylic acid monomer having at least oneionised sulphonate substituent (thereby avoiding any need to effectneutralisation subsequent to polyester formation). (Alternatively, alkylcarboxylic acid ester groups may be used in place of the carboxylic acidgroups as ester-forming groups). Such a monomer will therefore be partof the acid component used in the polyester synthesis.

Preferred polybasic carboxylic acids which can be used to form thepolyester have two or three carboxylic acid groups. For example, one canuse C₄ to C₂₀ aliphatic, alicyclic and aromatic compounds having two ormore carboxy groups and their ester forming derivatives (e.g. esters,anhydrides and acid chlorides), and dimer acids such as C36 dimer acids.Specific examples include adipic acid, fumaric acid, maleic acid,succinic acid, itaconic acid, sebacic acid, nonanedioic acid,decanedioic acid, 1,4-cyclohexanedicarboxylic acid,1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid,terephthalic acid, isophthalic acid, phthalic acid andtetrahydrophthalic acid and their acid chlorides. Anhydrides includesuccinic, maleic, phthalic and hexahydrophthalic anhydrides.

Preferred polyols which can be used to form the polyester include thosehaving from 2 to 6, more preferably 2 to 4 and especially 2 hydroxylgroups per molecule. Suitable polyols having two hydroxy groups permolecule include diols such as 1,2-ethanediol, 1,3-propanediol,1,4-butanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol (neopentylglycol), the 1,2-, 1,3- and 1,4-cyclohexanediols and the correspondingcyclohexane dimethanols, diethylene glycol, dipropylene glycol, anddiols such as alkoxylated bisphenol A products, e.g. ethoxylated orpropoxylated bisphenol A. Suitable polyols having three hydroxy groupsper molecule include triols such as trimethylolpropane (1,1,1-tris(hydroxymethyl)ethane). Suitable polyols having four or more hydroxygroups per molecule include pentaerythritol(2,2-bis(hydroxymethyl)-1,3-propanediol) and sorbitol(1,2,3,4,5,6-hexahydroxyhexane).

Compounds having two or more groups which readily undergo an estercondensation reaction and have one or more sulphonate groups aredicarboxylic acid monomers having at least one ionised sulphonate group.Examples of such compounds are aromatic dicarboxylic acids having anionised sulphonate group, for example those of the formula:

wherein M is a cation (preferably sodium, lithium or potassium); andeach R^(c) independently is H, a cation or C₁₋₄-alkyl (preferably methylor ethyl). Preferred compounds of the above formula are of formula:

wherein M and R^(c) are as defined above. Particularly preferred is themono sodium salt (one R^(c) is H, the other is Na), this material beingknown as sodio-5-sulphoisophthalic acid (SSIPA).

Other useful compounds which have two or more groups which readilyundergo an ester condensation reaction and have one or more sulphonategroups are dihydroxy monomers having at least one sulphonate group,especially those of the formula:

wherein M is as hereinbefore defined above and each R^(d) independentlyis alkylene, preferably C₂₋₄-alkylene. Preferred compounds of the aboveformula are:

wherein M is as hereinbefore defined.

Polyesters bearing ionised carboxy groups can be prepared by variousmeans. For example, if the hydroxyl component of the reactants isstoichiometrically in excess of the acid component, ahydroxyl-terminated polyester can be formed, which may be subsequentlyconverted to a carboxy terminated polyester by wholly or partiallyreacting the hydroxyl groups with an appropriate reagent (e.g. an acidanhydride or a dicarboxylic acid). Alternatively, terminal carboxyfunctionality may be directly introduced by employing an appropriatestoichiometric excess of the acid component reactants. In anotheralternative, chain-pendant carboxy groups may be introduced by usingreagents such as dimethylol propionic acid (DMPA) since if appropriatereaction condition are employed (e.g. polymerisation temperature below150° C.) the hindered carboxy group thereof does not take part to anysignificant extent in the ester-forming reactions during the polyestersynthesis and the DMPA effectively behaves as a simple diol.Chain-pendant and/or terminal carboxy groups could also be introduced byemploying a tri- or higher functionality carboxylic acid or anhydride inthe polyester synthesis, for example, trimellitic acid or anhydride.Combinations of the above procedures could also be used. It is thus seenthat terminal or side-chain carboxy groups or both can be introduced asdesired. These can be fully or partially neutralised with an appropriatebase to yield ionised carboxy groups. The counter ions used may be asfor the ionised sulphonate groups described above (apart from H⁺ sincethe carboxylic acid groups themselves are normally insufficientlyionised to provide a significant amount of ionised carboxygroups—although F substituents would increase acid strength), withalkali metal ions such as Na⁺, Li⁺ and K⁺ again being particularlypreferred, and ammonium and organic amine derived cations less preferredbecause some have an undesirable odour.

The water-dissipatable polyester may optionally have hydrophilicnon-ionic segments, for example within the polyester backbone (i.e.in-chain incorporation) or as chain-pendant or terminal groups. Suchgroups may act to contribute to the dispersion stability or evenwater-solubility of the polyester. For example, polyethylene oxidechains may be introduced into the polyester during its synthesis byusing as part of the hydroxyl component, ethylene oxide-containing mono,di or higher functional hydroxy compounds, especially polyethleneglycols and alkyl ethers of polyethylene glycols, examples of whichinclude:

wherein R^(e) is C₁₋₂₀-alkyl, preferably C₁₋₄-alkyl, more preferablymethyl; n is 1 to 500; and p is 1 to 100.

A small segment of a polyethylene oxide chain could be replaced by apropylene oxide or butylene oxide chain in such non-ionic groups, butshould still contain ethylene oxide as a major part of the chain.

The amount of ionised sulphonate and/or carboxy groups present in thepolyester should be sufficient to provide or contribute towater-dissipatability of the polyester, although it should not be sohigh as to render the resulting polyester unacceptably water-sensitive.This amount will depend, inter alia, on factors such as thehydrophilicity/hydrophobicity of units provided by other monomers in thepolyester synthesis or any surfactants (if used), and also the relativeproportions of ionised sulphonate/carboxy groups. With regard to thelast mentioned point, ionised sulphonate groups are more effective atproviding or contributing to water-dissipatability than ionised carboxygroups and so can be used at considerably lower levels in comparison toionised carboxy groups.

If the polyester is wholly or predominantly sulphonate stabilised (bywhich is meant the water dissipatability-providing groups are providedwholly or predominately by ionised sulphonate groups). The ionisedsulphonate group content is preferably within the range from 7.5 to 100milliequivalents (more preferably 10 to 75 milliequivalents andparticularly 11 to 56 milliequivalents) per 100 g of polyester. Whenusing SSIPA as the monomer for providing the ionised sulphonate groups,the amount of this monomer used in the polyester synthesis, based on theweight of all the monomers used in the polyester synthesis, will usuallybe within the range from 2 to 20% by weight (more usually 3 to 15% byweight). The carboxylic acid value (AV) of the polyester which ispredominantly sulphonate stabilised, i.e. an AV based on the carboxylicacid groups only (i.e. excluding sulphonate groups) will generally bewithin the range of from 0 to 100 mgKOH/g, more preferably 0 to 50mgKOH/g, especially 0 to 25 mgKOH/g, more especially 0 to 10 mgKOH/g.

If the polyester is predominantly stabilised by ionised carboxy groups,the carboxylic acid value AV of the polyester is preferably within therange of from 20 to 140 mgKOH/g (more preferably 30 to 100 mgKOH/g).

Usually, the polyester is either predominantly sulphonate-stabilised orpredominantly carboxylate stabilised (preferably the former).

If the polyester contains polyethylene oxide chains, the polyethyleneoxide chain content should preferably not exceed 25% by weight (and morepreferably should not exceed 15% by weight), based on the total weightof the polyester, in order to avoid unacceptable water-sensitivity.Therefore the amount is preferably 0 to 25% by weight (more preferably 0to 15% by weight) based on the total weight of polyester.

The water-dissipatable polyester preferably has a number averagemolecular weight Mn of up to 30,000. The Mn is preferably in the rangefrom 500 to 30,000, more preferably 1000 to 25,000, especially 2000 to20,000. These Mn lead to particularly good storage stability for theresultant inks. The measurement of Mn is well known to those skilled inthe art, and may for example be effected using gel permeationchromatography in conjunction with a standard polymer such aspolystyrene or polymethylmethacrylate of known molecular weight.

In an alternative embodiment the Mn is up to 10000, up to 3000 or up to2000. The minimum value for Mn in these embodiments is 500 or 750. Forexample Mn is in the range from 500 to 2500 or 750 to 2500 or 750 to2100.

The water-dissipatable polyester preferably has a hydroxyl number offrom 0 to 225 mg KOH/g, more preferably 0 to 125 mg KOH/g, especiallyfrom 0 to 50 mgKOH/g. In an alternative embodiment the hydroxyl numberis from 20 to 350 mg KOH/g or 20 to 200 mg KOH/g.

The ink preferably has a pH or 5 to 9, more preferably 5.5 to 8,especially 6 to 7.5. These preferences are based on increased inkstability.

The Tg of the water-dissipatable polyester (i.e. the temperature atwhich the polymer changes from a glassy, brittle state to a plastic,rubbery state) is preferably in the range −38° C. to 105° C., morepreferably −20 to 70° C., especially −10° C. to 60° C.

The esterification polymerisation processes for making the polyestersfor use in invention composition are known and need not be describedhere in more detail. Suffice to say that they are normally carried outin the melt using catalysts, for example a tin-based catalyst, and withthe provision for removing any water or alcohol formed from thecondensation reaction.

The water-dissipatable polyester may be dissipated in water by addingthe solidified melt directly into water. The solidified melt ispreferably in a form such as flake (which can often be obtained directlyfrom the melt) or comminuted solid (obtained for example by grinding).Alternatively, water can be added directly to the hot polyester meltuntil the desired solids content/viscosity is reached. Still further,the polyester may be dissipated in water by adding an aqueouspre-dissipation (or organic solvent solution) of the polyester to thewater phase.

The water-dissipatable polyesters normally do not need an externalsurfactant when being dissipated into water, although such surfactantsmay be used to assist the dissipation if desired and in some cases canbe useful in this respect because additional surfactants reduce therequired amount of dissipating groups (i.e. sulphonate, and (monoalkoxy)polyalkylene chains if used).

Water-dissipatable polyesters can also be purchased from Eastman KodakCompany and Zeneca Limited. Examples include Eastman AQ29D and AQ55W.

The water-dissipatable polymer may also be formed by performing freeradical polymerisation of olefinically unsaturated monomers in thepresence of a polyester. This gives what could be called apolyester-acrylic hybrid. Olefinically unsaturated monomers which can beused include olefinically unsaturated carboxy functional monomers, e.g.acrylic acid, methacrylic acid, fumaric acid, itaconic acid andβ-carboxyethyl acrylate; olefinically unsaturated monomers which arefree from carboxy and hydroxy groups, e.g. 1,3-butadiene, isoprene,styrene, vinylidene halides, vinylidene esters and esters of acrylicacid and methacrylic acid, e.g. methyl (meth)acrylate, ethyl(meth)acrylate n-butyl (meth)acrylate and 2-ethyl hexyl (meth)acrylate;and olefinically unsaturated monomers having a hydroxy group e.g.N-methylol (meth)acrylamide and hydroxy C₂₋₈-alkyl esters of(meth)acrylic acid. If the polyester has been prepared using a componentwhich has unsaturation therein, e.g. fumaric acid, maleic acid ormuconic acid or allyl-containing dihydroxy or dicarboxy compounds, theproduct from the polyesterification reaction will have unsaturationincorporated into its structure which can take part in the free radicalpolymerisation to give a graft copolymer. The free radicalpolymerisation processes use a free-radical generating initiator systemsuch as (for example) the redox radical initiator system tertiarybutylhydroxide/isoascorbic acid and will take place in the aqueousphase, rather than in the melt. However, excessive amounts of acrylicpolymer (whether formed in the presence of polyester which hasunsaturation or is free from unsaturation) often leads to adeterioration in ink properties and it is preferred that no acrylicpolymer is present or, if its is present, the amount is less than 40%,preferably less than 30%, more preferably less than 10% by weightrelative to the weight of polyester.

Alternatively polyesters used in this invention which have unsaturatedlinkages incorporated into their structures may also be mixed withultra-violet curable monomers and oligomers such that the polyester willcross-link on exposure to ultra-violet radiation. These monomers andoligomers are known in the art and include compounds such as(meth)acrylates of polyhydric alcohols, (meth)acrylates of polyhydricalcohol glycidyl ethers, (meth)acrylates of polyethylene glycols,(meth)acrylates of addition products of polyhydric alcohols and ethyleneoxide and reaction products of a polybasic add anhydride and a hydroxylgroup-containing (meth)acrylic ester. A photopolymerisation initiator isused and this may be selected from, for example, azides, ketone such asacetophenone or benzophenone and their derivatives, ketals such asbenzyl dimethyl ketal, peroxides such as benzoyl peroxide, benzoin,benzoin ethers, acyl phosphine oxides or aryl sulphonium salts such asdiphenyl-(4-phenylthio)-phenyl sulphoniumtetrafluorophosphate. One ormore photopolymerisation initiators may be used, optionally with asensitising agent. Suitable sensitising agents include aminobenzoates,alkanolamines and substituted thioxanthones.

Additionally the polyester used in this invention which containunsaturated linkages may be cross-linked by electron beam radiationwithout the need for additional cross-linking monomers/oligomers andinitiators. Cross-linking substantially improves the chemical andthermal resistance of the polyester and is desirable in the preparationof LCD colour filters.

The Dyes

The mixture of dyes may be a mixture of disperse dyes, a mixture ofsolvent soluble dyes or a mixture of one or more disperse dyes with oneor more solvent soluble dyes.

The disperse or solvent-soluble dye is preferably a water-insoluble dyewhich is soluble or dispersible in the mixture of the water-misciblesolvent, water-immiscible solvent and water-dissipatable polyester.Disperse and solvent soluble dyes are distinct from pigments in thatpigments are insoluble in organic solvents and polyesters whereasdisperse and solvent soluble dyes are soluble in organic solvents.Useful classes of disperse and solvent soluble dyes includewater-insoluble anthraquinones, phthalocyanines, pyrrolines,triphenodioxazines, methines, benzodifuranones, coumarins, indoanilines,benzenoids, xanthenes, phenazines, solvent soluble sulphur dyes,quinophthalones, pyridones, aminopyrazoles, pyrollidines, styrylics andazoics. Examples of preferred azoics are monoazo, disazo and trisazodisperse each of which are optionally metallised and solvent solubledyes; especially preferred azoics contain heterocyclic groups. TheColour Index International lists suitable disperse and solvent solubledyes, examples of which include Solvent Blue 63, Disperse Blue 24,Solvent Black 3, Solvent Black 35 and Disperse Red 60.

Further examples of disperse dyes are given in the Colour Index, 3rdEdition, Volume 2, pages 2483 to 2741 and further examples of solventsoluble dyes are given in Volume 3, pages 3566 to 3647 and each of thesedyes is included herein by reference Preferred dyes for use in thepresent invention include:

The Inks

The ink compositions preferably exist as a solution, emulsion,micro-emulsion, dispersion or micelle.

Preparation of The Inks

The present ink compositions may be prepared by dissolving the dye in amixture of an organic solvent, preferably a water-immiscible organicsolvent (e.g. benzyl alcohol) and water miscible organic solvent(s), andadding this solution to a solution of the water-dissipatable resin inwater and mixing, e.g. by stirring or sonication. The inks may beprepared at any temperature, for example between 5 and 85° C.,preferably at a temperature from 15 to 30° C.

The water-dissipatable polyester may also be dyed by heating awater-dissipatable polyester and a disperse dye or solvent soluble dyeat an elevated temperature, for example at a temperature in the range 35to 150° C., preferably from 40 to 90° C. This dyeing may be performed onthe solid polyester or a solution of the polyester in water and/or anorganic solvent. Alternatively, the solid water-dissipatable polyesterresin and the disperse or solvent soluble dye are dissolved in anorganic solvent and the solvent is removed by evaporation. This gives aclear, intensely coloured polyester which may then be diluted withwater, a water-miscible solvent and an organic solvent to give an ink.

A particularly useful process for the preparation of an ink according tothe invention comprises step a) and optionally step b) wherein: step a)comprises mixing together:

(i) a solution of a disperse dye or a solvent soluble dye or a mixtureof such dyes in a water-immiscible organic solvent; and

(ii) a water-dissipatable polyester, optionally in water; step b)comprises mixing the product of step a) with water; provided that eitheror both of (i) and (ii) further contains a water-miscible organicsolvent.

As inks of the invention contain water, step b) will usually benecessary when component (ii) does not contain water. If desired step b)may be performed even if water is present from step a). The mixingtogether referred to in step a) is of components (i) and (ii).

The above process leads to a particularly good up-take of dye by thepolyester to give intensely coloured inks.

Water-Immiscible Organic Solvents

Suitable water-immiscible organic solvents include aromatichydrocarbons, e.g. toluene, xylene, naphthalene, tetrahydronaphthaleneand methyl naphthalene; chlorinated aromatic hydrocarbons, e.g.chlorobenzene, fluorobenzene, chloronaphthalene and bromonaphthalene;esters, e.g. butyl acetate, ethyl acetate, methyl benzoate, ethylbenzoate, benzyl benzoate, butyl benzoate, phenylethyl acetate, butyllactate, benzyl lactate, diethyleneglycol dipropionate, dimethylphthalate, diethyl phthalate, dibutyl phthalate, di (2-ethylhexyl)phthalate; alcohols having six or more carbon atoms, e.g. hexanol,octanol, benzyl alcohol, phenyl ethanol, phenoxy ethanol, phenoxypropanol and phenoxy butanol; ethers having at least 5 carbon atoms,preferably C₅₋₁₄ ethers, e.g. anisole and phenetole; nitrocellulose,cellulose ether, cellulose acetate; low odour petroleum distillates;turpentine; white spirits; naphtha; isopropylbiphenyl; terpene;vegetable oil; mineral oil; essential oil; and natural oil; and mixturesof any two or more thereof. Benzyl alcohol is especially preferred.

Water-Miscible Organic Solvents

Suitable water-miscible organic solvents include C₁₋₅-alkanols, e.g.methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol,tert-butanol and isobutanol; amides, e.g. dimethylformamide anddimethylacetamide; ketones and ketone alcohols, e.g. acetone anddiacetone alcohol; C₂₋₄-ether, e.g. tetrahydrofuran and dioxane;alkylene glycols or thioglycols containing a C₂-C₆ alkylene group, e.g.ethylene glycol, propylene glycol, butylene glycol, pentylene glycol andhexylene glycol; poly(alkylene-glycol)s and thioglycol)s, e.g.diethylene glycol, thiodiglycol, polyethylene glycol and polypropyleneglycol; polyols, e.g. glycerol and 1,2,6-hexanetriol; and lower alkylglycol and polyglycol ethers, e.g. 2-methoxyethanol,2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy) ethanol,2-(2-butoxyethoxy)ethanol, 3-butoxypropan-1-ol,2-[2-(2-methoxyethoxy)-ethoxy]ethanol,2-[2-(2-ethoxyethoxy)ethoxy]-ethanol; cyclic esters and cyclic amides,e.g. optionally substituted pyrrolidones; sulpholane; and mixturescontaining two or more of the aforementioned water-miscible organicsolvents. Preferred water-miscible organic solvents are C₁₋₆-alkyl monoethers of C₂₋₆-alkylene glycols and C₁₋₆-alkyl mono ethers ofpoly(C₂₋₆-alkylene glycols).

Preferred Ink Formulations

The ratio of water-miscible organic solvent to water-immiscible organicsolvent is preferably 19:1 to 1:1, more preferably 8:1 to 1:1,especially 5:1 to 1:1.

The amount of said dye(s) and water-dissipatable polyester contained inthe ink will vary according to the depth of shade required. Typically,however, the ink will comprise

(a) from 0.1 to 20 parts, more preferably 0.5 to 10 parts, especially0.5 to 2.0 parts of said dye(s);

(b) from 0.5 to 50 parts, more preferably 2 to 20 parts, especially 8 to12 parts of a water-dissipatable polyester,

(c) from 40 to 90 parts, more preferably from 50 to 80 parts of water;

(d) from 2 to 30 parts, more preferably 5 to 15 parts, especially from 8to 12 parts of a water-immiscible organic solvent; and

(e) from 2 to 60 parts, more preferably from 5 to 25 parts, especiallyfrom 10 to 20 parts of a water-miscible organic solvent;

wherein all parts are by weight and the total number of parts of(a)+(b)+(c)+(d)+(e) add up to 100.

The number of parts of the water-dissipatable polyester is calculated ona 100% solids basis. For example 50 g of a 20% solids polyester is takenas 10 g of polyester.

The preferred water-immiscible solvent is an alcohol having at least sixcarbon atoms, especially benzyl alcohol.

The water-miscible solvent is preferably:

(a) a cyclic ester or cyclic amide (especially an optionally substitutedpyrrolidone);

(b) a water-miscible C₁₋₆-alkyl mono ether of a C₂₋₆-alkylene glycol orC₁₋₆-alkyl mono ether of poly(C₂₋₆-alkylene glycol); or

(c) a mixture of (a) and (b).

The ink compositions preferably comprise from 0.5 to 50%, morepreferably from 2 to 20% and especially from 8 to 12% of thewater-dissipatable polyester; from 0.5 to 20%, more preferably from 0.5to 10% and especially from 0.5 to 2.0% of the disperse or solventsoluble dye or combination thereof; from 2 to 30%, more preferably from5 to 15% and especially from 8 to 12% of the water-immiscible organicsolvent; from 2 to 60%, more preferably from 5 to 25% and especiallyfrom 10 to 20% of the water-miscible solvent with substantially the restof the ink composition being water provided that at least 30% of the inkcomposition is water. All percentages are %w/w (i.e. by weight).

An especially preferred ink composition comprises from 0.5 to 5.0% ofdisperse or solvent soluble dye or mixture thereof, from 5 to 30% ofwater immiscible solvent, from 5 to 30% of sulphonated polyester resin,from 0.1 to 30% of water miscible solvent, optionally from 0.1 to 2% ofan organic base (e.g. such as morpholine or its derivatives or analkanolamine) with the remainder of the composition comprisingsubstantially water.

The water-immiscible solvent preferably has a solubility in water at 20°C. of up to 50 g/l. The water-miscible solvent preferably has asolubility in water at 20° C. of more than 50 g/l.

The preferred optionally substituted pyrrolidones are 2-pyrrolidone,dimethyl pyrrolidone N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone andN-(2-hydroxyethyl)-2-pyrrolidone and mixtures thereof.

The inks optionally contain a biocide, for example Proxel GXL (Proxel isa trade mark of Zeneca Limited) or Kathon (Kathon is a trade mark ofRohm and Haas), a fungicide, a rheological agent, e.g. a wax (e.g.beeswax), a clay (e.g. bentonite), an IR absorber, for example Projet900NP(Projet is a trade mark of Zeneca Limited), a fluorescentbrightener, for example C. I. Fluorescent Brightner 179 and/or UVabsorber, for example hydroxy phenylbenzotriazole. Furthermore the inkcompositions optionally contain a surface active agent, wetting agentand/or emulsifiers, for example those described in McCutcheon'sEmulsifiers and Detergents 1996 International Edition or in SurfactantsEuropa 3rd Edition 1996 each of which is incorporated herein byreference.

Inks according to the invention have an advantage over inks containingpigments in that less dye is usually required than would be the case fora pigment, expensive milling is avoided, the inks are less likely toform a precipitate on standing, a far greater variety of shades areavailable and the resultant prints have good transparency. The latterquality is particularly important for the production of colouredsubstrates which require transparency, for example over-head projectorslides and colour filters used in LCD television screens. The inks ofthe present invention also benefit from good light- and water-fastness.

A valuable feature of the invention is the low tendency for blocking thenozzles of thermal ink jet printers. Many other water dispersiblepolymer inks work poorly or even not at all in thermal printers. Inks ofthe invention form discrete droplets on the substrate with littletendency for diffusing. Consequently sharp images can be obtained,resulting in excellent print quality and little if any bleed betweencolours printed side-by side.

Printing Process

According to a further feature the present invention provides a processfor the coloration of a substrate comprising printing an ink onto thesubstrate using an ink jet printer, characterised in that the ink is ashereinbefore defined in relation to the present invention.

The ink jet printer emits droplets of the ink onto a substrate from anozzle without bringing the nozzle into contact with the substrate.Preferably the ink jet printer is a thermal or piezoelectric ink jetprinter.

The substrate is preferably a paper, a transparent material (e.g. anoverhead projector slide) or a textile material. Preferred textilematerials are cotton, polyester and blends thereof.

When the substrate is a textile material the process for printing animage thereon according to the invention preferably further comprisesthe step of heating the resultant printed textile, preferably to atemperature of 50° C. to 250° C.

Optical Filters

The inks of the present invention may also be used for the preparationof colour filters, for example those used in flat bed displays.

According to a further feature of the present invention, there isprovided a process for preparing an optical filter comprising applyingto a transparent substrate, an ink according to the invention therebyforming a coloured cross-linked polymeric coating on the substrate.Preferably the process comprises applying a red, green and blue inkaccording to the invention. The red, green and blue inks are preferablyapplied as discrete filler regions, preferably in triads.

The ink used to prepare the optical filter preferably contains a polymerprecursor, for example one or more of the olefinically unsaturatedmonomers mentioned above and an initiator. Dyes contained in the inksmay contain one or more substituents such as hydroxy, carboxylic acid,acid anhydride, amine, substituted amine, alkene and epoxide which arecapable of forming a covalent bond with the polymer precursor andthereby further improve the chemical and thermal resistance of thecoating.

The cross-linked polymeric coating may be formed on a substrate to whichthe ink will bond, adhere, absorb or fuse. Suitable transparentsubstrates include glass; plastics films and plates such as those ofpolyvinylalcohol, polyester, polyvinylchloride, polyvinylfluoride,polycarbonate, polystyrene, polyamide or polyimide. A preferredsubstrate is glass.

The substrates may be pre-treated to improve bonding, adhesion,absorption, fusion or spreading of the cross-linked polymeric coating onthe substrate. Suitable pre-treatments include plasma ashing in whichthe substrate is placed in an oxygen atmosphere and subjected to anelectrical discharge or application of an adhesion promoter such as asilane.

In the present process the cross-linking of the ink may be initiatedthermally, chemically or photochemically. Similarly any reaction betweenthe polymer precursor(s) and dye(s) may be initiated thermally,chemically or photochemically. The reaction between polymer precursor(s)and dye(s) in the inks may, where they are sufficiently reactive, beinitiated simply by mixing the polymer precursor(s) and inks eachoptionally in a liquid medium and allowing the mixture to air dry.

Where the polymer precursor used in processes for forming an opticalfilter is one which is itself capable of cross-linking when cured (e.g.melamine-formaldehyde resin condensate) no additional cross-linkingagent need be added to the mixture of the ink and polymer precursor.However, where the polymer precursor is one which is not itself capableof extensive cross-linking, it may be desirable to add a cross-linkingagent to the mixture of ink and polymer precursor. The use ofcross-linking agents is well known in the polymer art, and the choice ofcross-linking agent will be readily made by one skilled in the art.

Chemical initiation may be achieved by the addition of suitable reactiveagents such as epoxides, acids or acid anhydrides.

Photochemical initiation for polyesters having unsaturated linkagesincorporated into their structure may be achieved by electron beamradiation or by the addition of ultra violet curing monomers andoligomers and initiators, for example azides, ketone such asacetophenone or benzophenone and their derivatives, ketals such asbenzyl dimethyl ketal, peroxides such as benzoyl peroxide, benzoin,benzoin ethers, acyl phosphine oxides or aryl sulphonium salts such asdiphenyl-(4-phenylthio)-phenyl sulphoniumtetrafluorophosphate followedby irradiation with UV or visible light.

Thermally initiated cross-linking and reaction is preferred because ithas the advantage of simplicity.

The ink is preferably applied to the transparent substrate by a printingprocess, for example by a printing process such as flexographic, off-setlithographic, gravure, intaglio, ink-jet, dye diffusion thermal transferand screen printing processes. The printing process is preferablyink-jet printing, especially thermal or piezoeletric ink-jet printing.The principles and procedures for ink jet printing are described in theliterature for example in High Technology Applications of OrganicColorants, P. Gregory, Chapter 9 ISBN 0-306-43637-X.

Optical filters, alternatively known as colour filters, are used inliquid crystal displays, for example in small television receivers.

Where the process used for applying the ink to the transparent substrateis ink jet printing, it is possible to achieve printing of all threeprimary colours (red, green and blue) simultaneously to form triads orany desired groupings of filter elements, for example by using aprinting head having outlets for three coloured inks of the invention.

Ink Jet Printing of Textiles

According to a further aspect of the present invention there is provideda process for the coloration of a synthetic textile material with an inkaccording to the invention which comprises the steps:

(i) applying the ink composition to the textile material by ink jetprinting; and

(ii) heating the printed textile material at a temperature from 50° C.to 250° C. to fix the dye on the material.

The application of the ink composition to the textile material, stage(i) of the present process, is preferably effected by drop on demand(DOD) or continuous flow ink jet printing. Where the ink jet printingtechnique involves the charging and electrically-controlled deflectionof drops the ink preferably also contains a electrically-conductingmaterial, e.g. an ionised salt to enhance and stabilise the chargeapplied to the drops. Suitable salts for this purpose are alkali metalsalts of mineral acids.

After application of the ink composition, it is generally desirable toremove water from the printed textile material at relatively lowtemperatures (<100° C.) prior to the heat applied to fix the dye on thetextile material. This has been found to minimise the diffusion of thedye from printed to non-printed regions. Removal of water is preferablyby heat, such as by exposure to hot air or to infra-red or micro-waveradiation.

In stage (ii) of the present process, the printed textile material ispreferably submitted to a short heat treatment, preferably after removalof water by low-temperature drying, at a temperature from 100° C. to200° C. For a period of up to 20 minutes. If a steam (wet) heattreatment is used, the printed material is preferably maintained at100-105° C. for from 5 to 15 minutes whereas if a dry heat treatment isemployed the printed material is preferably maintained at 140-160° C.for from 2 to 8 minutes.

After allowing the textile material to cool, unfixed dye and otheringredients of the dye compositions may be removed from the textilematerial by a washing sequence, involving a series of hot and coldwashes in water and aqueous detergent solutions before the textilematerial is dried.

According to a further aspect of the present invention there is provideda textile material, especially a synthetic textile material or a blendof synthetic textile material with cellulosic material, coloured withany of the ink compositions according to the present invention or bymeans of a process according to the present invention.

Transfer Printing

According to a further aspect of the present invention there is provideda transfer printing sheet for synthetic textile materials comprising asubstrate and a coating comprising a water-dissipatable polyester and adisperse or a solvent soluble dye or a mixture of such dyes,characterised in that the coating has been applied to the sheet using anink according to the invention, preferably by ink jet printing.

A preferred transfer printing process comprises the steps:

(i) applying an ink according to the invention to a first substratethereby resulting in a first substrate carrying an image;

(ii) bringing the image resulting from step (i) into contact with asecond substrate;

(iii) heating the first substrate thereby transferring the image to thesecond substrate.

This latter process can be used to prepare T-shirts, clothing andnovelty goods in general.

The heating in step (iii) is preferably at a temperature of from 60 to250° C., more preferably from 150 to 220° C. The period of heating ispreferably from 1 to 45 seconds, more preferably from 5 to 30 seconds.Consequently the first substrate is preferably capable of withstandingthese temperatures for the times indicated.

The first substrate is preferably selected from paper and foil, forexample aluminium foil.

The invention is further illustrated by the following examples in whichall parts and percentages are by weight unless specified otherwise.

EXAMPLE 1

Stage 1—Preparation of a Water-Dissipatable Polyester

To a glass reactor fited with distillation column and condenser werecharged ingredients A, B, D, F, G and 50% of C and 50% of H. Thecontents were heated with stirring to a reaction temperature of 210° C.until the mixture was clear and the acid value was <10 mgKOH/g. At thispoint E and the remainder of C and H were charged and the temperatureraised to 230° C. The reaction was continued under reduced pressureuntil an acid value of 5.3 mgKOH/g was obtained. The resin was furthercharacterised by a hydroxyl value=27.6 mgKOHg, ICI Cone and Plateviscosity @ 125° C.=80 poises and a Tg (onset)=25.4° C. and a numberaverage molecular weight by end group analysis of approximately 2000.The resin was readily dispersed in warm distilled water to give a clearsolution having a solids content of 20% w/w.

Monomer Abbreviation Weight (g) neopentyl glycol A 206.25 diethyleneglycol B 82.5 isophthalic acid C 300 sodio-5-sulpho-isophthalic acid D75 adipic acid E 37.5 methoxy PEG 750 F 75 sodium acetate G 1.5 Fascat4101 H 0.75

Stage 2—Ink Preparation

A sample of CI Disperse Yellow 126 (from BASF, Dispersol Yellow D-7G) (1g) was dissolved in a mixture of benzyl alcohol (10 g) and 2-pyrrolidone(20 g) using a sonicator. A mixture of the water-dissipatable polyesterdescribed in Stage 1 (50 g, 20% w/w solution in water) and water (19 g)was added and the mixture was shaken to give a homogenous ink having theformulation:

Component Amount (g) CI Disperse Yellow 126  1 Polyester from Stage 1 50 (20% solids) Benzyl alcohol (Immiscible)  10 2-pyrrollidone(Miscible)  20 Water  19 100

Stage 3—Ink Jet Printing Using the Inks

The ink described in Stage 2 was printed onto 2 commercially availableplain papers, as described below, using a Hewlett Packard thermalink-jet printer.

The resultant prints had very good colour strength and brightness(chroma) as indicated in Table 1 and showed very high water fastness.0.5 ml of water run down a test print only 5 minutes after printingproduced virtually no stain on the white paper.

The prints were irradiated with light using an Atlas Ci 35 weatherometerand the colour change (ΔE) measured after the time indicated in Table 1.

Paper XA is Xerox 4024 from Rank Xerox

Paper WC is Conqueror High White Wove 100 g/m² from Arjo WigginsLimited.

ROD is the reflected optical density of the resultant print.

TABLE 1 Paper ROD Chroma ΔE XA 0.84 78.03  7.59 @ 24 hours 11.01 @ 48hours 13.55 @ 72 hours  14.09 @ 100 hours WC 0.82 86.49  5.83 @ 24 hours 9.55 @ 48 hours 10.29 @ 72 hours  12.09 @ 100 hours

EXAMPLE 2

Stage 1—Dyeing of Water Dissipatable Polyester

C.I. Disperse Yellow 126 (from BASF) (1.2 g) was mixed with 60 g of a20% w/w aqueous solution of the polyester described in Example 1, Stage1 and heated with stirring at 80-90° C. for 30 minutes. The resultantdyed resin dispersion was cooled and filtered through a 0.45 μm membranefilter.

Stage 2—Ink Preparation

1.25 g of the dispersion from Stage 1 was mixed with benzyl alcohol (0.5g), thiodiglycol (0.75 g) and of distilled water (2.5 g) to give thefollowing ink:

Dyed resin dispersion from Stage 1 1.25 g (20% solids) Benzyl alcohol(immiscible)  0.5 g Thiodiglycol (miscible) 0.75 g Water  2.5 g  5.0 g

Stage 3—Ink Jet Printing Using the Ink

The ink described in Stage 2 was printed onto 2 commercially availablepapers as described below using a Hewlett Packard HP 560C thermalink-jet printer.

a) Gilbert Bond—plain paper from The Mead Corporation

b) HP Coated Ink Jet Printer paper Ref HP 51634Y from Hewlett Packard.

The ink fired very well with respect to the absence of nozzle blockageand continued firing over a period of time. The ink spread well on thepaper surface to give a homogenous print. Furthermore the ink had notendency to penetrate the bulk of the paper. Consequently ink “strikethrough” was very good.

EXAMPLES 3 AND 4

Further inks were prepared using the method of Example 2, Stage 2, withlower levels of benzyl alcohol as follows:

Ex 3 Ex 2 Dyed Resin Dispersion from Example 2, Stage 1 1.25 g 1.25 gThiodiglycol 0.75 g 0.75 g Benzyl Alcohol  0.3 g 0.15 g Water 2.70 g2.85 g 5.00 g 5.00 g

The printing performance of these inks was very similar to that fromExample 2.

Comparative Example 1

The ink preparation from Example 2, Stage 2 was repeated except that theimmiscible solvent (benzyl alcohol) was replaced by water to give an inkas follow:

Dyed Resin Dispersion from Example 2, Stage 1 1.25 g Thiodiglycol 0.75 gWater 3.00 g 5.00 g

This ink was printed as described in Example 2, Stage 3 and causedsevere firing problems. Not all the nozzles could be made to fire atonce and those that did fire blocked up quickly. The ink also showedpoor spreading performance on the paper such that the individual dropscould be seen and solid blocks of print could not be generated.

Examples 5-9 and Comparative Examples 2 and 3

In Examples 5-9 and comparative Examples 2 and 3 the following inkformulation was used, only the types of miscible and immiscible solventswere varied.

Dispersol Yellow D-7G (from BASF)  1% Morpholine  1% Water-ImmiscibleSolvent A 10% Water-Miscible Solvent B 20% 20% w/w aqueous polyesterfrom Example 1, Stage 1 50% water 18%

In all cases the dye, morpholine and solvents were mixed together andplaced in a sonic bath until all the dye had dissolved. The resinsolution and water were then added and the mixture shaken to give ahomogenous ink.

The inks were fired through a Hewlett Packard HP 560C printer onto Xerox4024 plain paper and the reflected optical density (ROD) and printbrightness (chroma) measured. The solvents used and results are shown inTable 2 below:

TABLE 2 Example Solvent A Solvent B ROD Chroma 5 Benzyl alcohol 2-P*0.745 73.45 6 Benzyl alcohol NMP* 0.725 76.43 7 EG-MS 2-P* 0.733 78.79 8Benzyl alcohol DEG-MME* 0.696 77.85 9 Benzyl alcohol 1:1, DEG-MBE*:0.698 77.61 2-P* Comp. 2 DEG* NMP* 0.375 45.23 Comp. 3 DEG-MBE* NMP*0.401 47.97 *a water-miscible organic solvent. EG-MS is ethylene glycolmono salicylate NMP is n-methyl-2-pyrrolidone DEG-MME is diethyleneglycol monomethyl ether DEG-MBE is diethylene glycolmonobutyl ether DEGis diethylene glycol 2-P is 2-pyrrolidone.

As can be seen from Table 2, comparative Examples 2 and 3 gave loweroptical density and chroma than Examples 5 to 9.

EXAMPLES 10-12

A sample of Methic Turquoise P Base (from Zeneca Limited) (1 g) wasmixed with benzyl alcohol (10 g), one or more water miscible solvents asdescribed below (20 g) and morpholine (1 g). This mixture was thenplaced in a sonic bath until all the dye had dissolved. 50 g of a 20%aqueous solution of the polyester described in Example 1, Stage 1 andwater (18 g) were then mixed with the dye solution and shaken to give ahomogenous ink.

These inks were then printed onto Conqueror High White Wove 100 gsmpaper using a Hewlett Packard HP 560C thermal ink jet printer.

The results described in Table 3 were obtained.

TABLE 3 Example Solvent ROD 10 2-P 0.773 11 1:1, 2-P: DEG-MME 0.800 121:1, 2-P: DEG-MBE 0.814

Abbreviations as for Table 2.

EXAMPLES 13-15

The ink formulations described in Table 4 were prepared in the samemanner as those in Examples 10-12:

TABLE 4 Example Component 13 14 15 Methic Turquoise P  1%  1%  1%Morpholine  1%  1%  1% Benzyl Alcohol - Immiscible Solvent 10% 10% 10%Ethylene glycol mono salicyate - Immiscible Solvent  5% Diethyleneglycol monobutyl ether - Miscible  5% 10% 10% Solvent 2-pyrrolidone -Miscible Solvent 10%  5%  5% Oxazolidone - Miscible Solvent  5%Imidazolidone - Miscible Solvent  5% 20% aqueous polyester from Example1, Stage 1 50% 50% 50% water 18% 18% 18%

The above inks were then printed onto the various plain papers using theHewlett Packard HP 560C thermal ink jet printer and the ROD were asdescribed in Table 5 below:

TABLE 5 Example Xerox 4025 Paper Gilbert bond Paper Conqueror Paper 13 —— 0.786 14 0.752 0.700 0.759 15 0.778 0.726 0.781

EXAMPLE 16

A sample of Lampranol Red 2BRN (C.I.Solvent Red 160) (from ZenecaLimited) (1 g) was mixed with ethylene glycol mono salicylate(immiscible solvent) (5 g), hexylene glycol (5 g) (miscible solvent),N-methyl-2-pyrrolidone (20 g) (miscible solvent) and morpholine (1 g).The mixture was held in a sonic batch until all the dye had dissolved.50 g of a 20% w/w aqueous solution of the polyester described in Example1, Stage 1 and water (18 g) were then added and the mixture shaken togive a homogenous and stable ink.

The ink was fired through a Hewlett Packard HP560C printer onto AdjoWiggins Conqueror paper. The resultant print had reflected opticaldensity of 0.67.

EXAMPLES 17-18

Inks of the formulations described in Table 6 were prepared in the samemanner as those described in Examples 10-16.

TABLE 6 Component Example 17 Example 18 Neozapon Pink 478 (C.I. SolventRed  2 g  2 g 127) ex BASF 20% w/w aqueous polyester from Example 50 g50 g 1, Stage 1 Morpholine  1 g  1 g Benzyl alcohol (immiscible solvent)10 g — Ethylene glycol mono salicylate (immiscible) —  5 g Hexyleneglycol (miscible) —  5 g 2-pyrrolidone (miscible) 20 g 20 g Water 17 g17 g

These inks were printed onto the plain paper using the Hewlett PackardHP560C printer and the resultant ROD are as shown in Table 7 below:

TABLE 7 Example ROD 17 1.134 18 1.025

EXAMPLES 19-21

Stage 1—Preparation of a Water-Dissipatible Polyester

To a glass reactor fitted with distillation column and condenser werecharged ingredients A, B, C, E, G, H and 50% of D and 50% of I. Thecontents were heated with stirring to a reaction temperature of 210° C.until the mixture was clear and the acid value was <10 mgKOH/g. At thispoint F and the remainder of D and I were charged and the temperatureraised to 230° C. The reaction was continued under reduced pressureuntil an acid value of 2.8 mgKOH/g was obtained. The resin was furthercharacterised by a hydroxyl value=19.7 mgKOHg, ICI Cone and Plateviscosity @ 125° C.=90 poises and a Tg (onset)=4° C. The number averagemolecular weight by end group analysis was 4987. The resin readilydispersed in warm distilled water to give a clear solution having asolids content of 20% w/w.

TABLE 8 Monomer Abbreviation Weight (g) neopentyl glycol A 15hexane-1,6-diol B 10 diethylene glycol C 10 isophthalic acid D 40sodio-5-sulpho-isophthalic acid E 10 adipic acid F 5 methoxy PEG 750 G10 sodium acetate H 0.2 Fascat 4101 I 0.1

Stage 2—Ink Preparation and Printing

Inks of the following formulations were prepared in the same manner asfor Examples 13-15.

TABLE 9 Component Ex 19 Ex 20 Ex 21 C.I. Solvent Orange 2  1 g C.I.Disperse Orange 13  1 g C.I. Disperse Orange 3  1 g Benzyl Alcohol 10 g10 g 10 g 2-Pyrrolidone 20 g 20 g 20 g 20% w/w aqueous solution ofpolyester from 50 g 50 g 50 g Stage 1 Water 19 g 19 g 19 g

These inks were then used to fill empty colour cartridges from anOlivetti JP450 ink jet printer. This printer was then used to print theinks on the following papers and the ROD measured.

Papers

Xerox 4024

Wiggins Conqueror High White Wove 100 gsm

ROD Measurements

TABLE 10 Example Xerox 4024 Paper Conqueror Paper 19 0.70 0.83 20 0.921.01 21 0.91 0.98

EXAMPLES 22-24

Stage 1—Preparation of a Water-Dissipatible Polyester

To a glass reactor fitted with distillation column and condenser werecharged ingredients A, B, D, E, F, G and 50% of C and 50% of H. Thecontents were heated with stirring to a reaction temperature of 210° C.until the mixture was clear and the acid value was <10 mgKOH/g. At thispoint the remainder of C and H were charged and the temperature raisedto 230° C. The reaction was continued under reduced pressure until anacid value of 9.4 mgKOH/g was obtained. The resin was furthercharacterised by a hydroxyl value=3.4 mgKOHg, ICI Cone and PlateViscosity @ 125° C.=>500 poises and a Tg (onset)=18° C. The numberaverage molecular weight by end group analysis was 8766. The resin wasreadily dispersed in warm distilled water to give a clear solutionhaving a solids content of 20% w/w.

TABLE 11 Monomer Abbreviation Weight (g) neopentyl glycol A 15diethylene glycol B 10 isophthalic acid C 45 sodio-5-sulpho-isophthalicacid D 10 Hexane-1,6-diol E 10 Methoxy PEG 750 F 10 Sodium acetate G 0.2Fascat 4101 H 0.1

Stage 2—Ink Preparation and Printing

The following inks were prepared in the same manner as for Examples13-15.

TABLE 12 Component Ex 22 Ex 23 Ex 24 Celestine Blue (from Aldrich)  1 gC.I Basic Blue 41  1 g Pro-jet Black Alc. Powder (from Zeneca Limited) 3 g Benzyl Alcohol 10 g 10 g 10 g 2-pyrrolidone 20 g 20 g 20 g 20% w/waqueous solution of polyester from stage 1 50 g 50 g 50 g Water 19 g 19g 17 g

These inks were printed onto plain paper using a Olivetti JP450 printeras described in Examples 19-21 and the ROD measurements were as follows:

Example Xerox 4024 Paper Conqueror Paper 22 0.51 — 23 0.75 — 24 1.031.07

EXAMPLES 25-28

A dye of the formula shown below:

was prepared by using stages 1a to 1d described below.

Stage 1a

2-Amino-1,1,3-tricyanopropene (66 g) was suspended in ethanol (500 ml)at 5° C. A solution of hydrazine hydrate (25 ml) in water (25 ml) wasthen added dropwise over 30 mins at 5-10° C. After heating under refluxfor 30 mins the reaction mixture was cooled to room temperature and thecrystalline product was isolated by filtration, washed well with waterand dried.

Stage 1b—3-(N,N-dibutylamino)acetanilide

3-Aminoacetanilide (186.2 g), 1-bromobutane (425 g), triethylamine (3/4g) and ethanol (1 litre) were heated under reflux for 64 hrs. Aftercooling to room temperature the reaction mixture was filtered to removetriethylamine hydrochloride and the solvent evaporated under reducedpressure to leave to a dark oil which was purified by chromatography onsilica gel. The product was crystallised by trituration under hexane.

Stage 1c—Preparation of

The product from Stage 1a (14.72 g) was suspended in a mixture of aceticacid (400 ml) and hydrochloric acid (60 ml) at 0-5° C. A solution ofsodium nitrite (8 g) in the minimum of water was then added over 20minutes. On completion of the addition the solution was stirred for afurther 30 minutes and the excess nitrous acid destroyed by the additionof saturated sulphamic acid solution. The resultant diazonium saltsolution was then added slowly to a solution the product from Stage 1b(26.4 g) in ethanol (500 ml) to which potassium acetate (50 g) had beenadded. After stirring for a further 60 minutes, water (800 ml) wasadded, and the product was isolated by filtration, washed well withwater and dried.

Stage 1d—Preparation of Dye 1

The product from Stage 1c (21 g), chloroacetonitrile (5 ml), 2-butanone(250 ml), water (50 ml) and sodium hydrogen carbonate (4.2 g) werestirred and heated under reflux for 4 hrs. After diluting with water (1litre) the crude product was isolated by extracting into dichloromethaneand purified by column chromatography on silica gel eluting with ethylacetate/hexane (1:1) to give Dye 1 as a red crystalline solid.

Stage 2—Ink Preparation

Inks of the following general formulation were prepared in the samemanner as for Examples 13-15:

Dye from Stage 1  1 g Immiscible solvent A 10 g 2-Pyrrolidone (SolventB) 20 g 20% w/w aqueous solution of polyester from Ex 22 Stage 1 50 gWater 19 g

The following immiscible solvents under the heading ‘Solvent A’ wereevaluated in the above formulation and all gave stable inks. With theexception of Example 29 all the inks were printed onto Xerox 4024 andConqueror paper using a Hewlett Packard HP 560C ink jet printer. Theinks gave good quality prints and the ROD was measured and recorded.

TABLE 13 ROD Xerox ROD - Example Solvent A Solvent B 4024 Conqueror 253-phenyl-1-propanol 2-P 0.87 0.8 26 4-methoxybenzyl alcohol 2-P 0.940.91 27 Ethyleneglycol mono 2-P 0.94 0.87 salicylate 28 Diethyl glycolmono hexyl 2-P 0.98 0.99 ether 29 Dichloromethane 2-P — —

Comparative Examples 4-5

Inks of the formulation described in Examples 25-28 were prepared inwhich the immiscible solvent (Solvent A) was replaced by the solventdescribed in Table 14. Problems of nozzle blockage and intermittentfiring were encountered when printing from a Hewlett Packard HP560Cprinter. The resultant prints were of very poor quality. The RODmeasurements of these prints are given below in Table 14.

TABLE 14 Comparative ROD (Xerox ROD (Conqueror Example Solvent A SolventB 4024 paper) paper) 4 Water 2-P 0.532 0.486 5 2-P 2-P — 0.562

What is claimed is:
 1. An ink composition comprising water, awater-dissipatable polyester bearing ionized sulphonate groups, adisperse dye or a solvent soluble dye or a mixture of such dyes, awater-immiscible organic solvent and a water miscible organic solvent.2. An ink composition according to claim 1 comprising: (a) from 0.1 to20 parts of said dye(s); (b) from 0.5 to 50 parts of awater-dissipatable polyester; (c) from 40 to 90 parts of water, (d) from2 to 30 parts of a water-immiscible organic solvent; and (e) from 2 to60 parts of a water-miscible organic solvent; wherein all parts are byweight and the total number of parts of (a)+(b)+(c)+(d)+(e) add up to100.
 3. An ink composition according to claim 1 or 2 wherein thewater-immiscible organic solvent is an aromatic hydrocarbon, achlorinated hydrocarbon, an ester, an alcohol having six or more carbonatoms, an ether having at least 5 carbon atoms, a low odour petroleumdistillate, turpentine, white spirits, naphtha, isopropyl biphenyl,terpene, vegetable oil, mineral oil, essential oil, a natural oil, or amixture of any two or more thereof.
 4. An ink composition accordingclaim 1 or 2 wherein the water-immiscible organic solvent is toluene,xylene, naphthalene, tetrahydronaphthalene, methyl naphthalene,chlorobenzene, fluorobenzene, chloronaphthalene, bromonaphtalene, butylacetate, ethyl acetate, methyl benzoate, ethyl benzoate, benzylbenzoate, butyl benzoate, phenylethyl acetate, butyl lactate, benzyllactate, diethylene glycol dipropionate, dimethyl phthalate, diethylphthalate, dibutyl phthalate, di(2-ethylbexyl)phthalate, hexanol,octanol, benzyl alcohol, phenylethanol, phenoxy ethanol, phenoxypropanol, phenoxy butanol, anisole, phenetole, or a mixture of any twoor more thereof.
 5. An ink composition according to claim 1 or 2 whereinthe water-immiscible organic solvent is benzyl alcohol.
 6. An inkcomposition according to claim 1 or 2 wherein the water-miscible organicsolvent is: (a) a cyclic ester or cyclic amide; (b) a water-miscibleC₁₋₆-alkyl mono ether of a C₂₋₆-alkylene glycol or C₁₋₆-alkyl mono etherof poly(C₂₋₆-alkylene glycol); or (c) a mixture of (a) and (b).
 7. Aprocess for the coloration of a substrate comprising printing an inkcomposition onto the substrate using an ink jet printer, characterizedin that the ink composition is as defined in claim 1 or
 2. 8. A processaccording to claim 7 wherein the substrate is a paper, a transparentmaterial or a textile material.
 9. A process for preparing an opticalfilter comprising applying to a transparent substrate an ink compositionaccording to claim 1 or 2, thereby forming a colored cross-linkedpolymeric coating on the substrate.
 10. A process for the coloration ofa synthetic textile material with an ink composition according to claim1 or 2 which comprises the steps: (i) applying the ink composition tothe textile material by ink jet printing; and (ii) heating the printedtextile material at a temperature from 50° C. to 250° C. to fix the dyeon the material.
 11. A transfer printing process comprising the steps:(i) applying an ink composition according to claim 1 or 2 to a firstsubstrate thereby resulting in a first substrate carrying an image; (ii)bringing the image resulting from step (i) into contact with a secondsubstrate; (iii) heating the first substrate thereby transferring theimage to the second substrate.
 12. A process for the preparation of anink composition according to claim 1 or 2 which comprises mixingtogether (i) a solution of a disperse dye or a solvent soluble dye or amixture of such dyes in a water-immiscible organic solvent; and (ii) awater-dissipatable polyester, optionally in water; provided that eitheror both of (i) and (ii) further contains a water-miscible organicsolvent.
 13. A process according to claim 12, which further comprisesmixing the resultant mixture with water.
 14. An ink composition to claim1 wherein the ratio of the water-miscible organic solvent towater-immiscible organic solvent is 19:1 to 1:1 by weight.